Roger Sterling (John Slattery) grew a mustache for the show’s seventh and final season.

(James Minchin III/AMC)

Roger Sterling’s mustache was real — sort of

The second half of Season 7 kicked off with the memorable debut of Roger Sterling’s handlebar mustache, leading viewers to wonder whether John Slattery grew an actual mustache for the role.

While Slattery originally wouldn’t reveal whether it was real or fake, he recently told Deadline that he really did grow the ‘stache.

“I grew it myself and they took a mold of it and made one. Then I shaved it off because Matt didn’t want me to walk around with a mustache and give away the secret,” he revealed.

“They filled it out a bit as (mine) wasn’t quite as complete as Roger’s but it was along the same lines,” he added. “It was really all about the secrecy though, so I wasn’t walking around in my life six months before the episode was shot with a giant mustache.”

A “Mad Men” crew member’s dream came true

The show’s cast and crew filmed a singalong to “Bye Bye Birdie” for the Season 3 wrap party, since the song had been prominently featured on the show.

One of the series’ crew members used the video to send a message to creator Matthew Weiner: “Matt, make my dream come true! Next season please let me jump out of a cake!”

She had to wait until Season 7, but she got her wish: The crew member indeed jumped out of a cake in her cameo as a burlesque dancer in “The Milk and Honey Route.”

A “Mad Men” crew member requested to jump out of a cake on an episode of the show, and got her wish in “The Milk and Honey Route.”

(YouTube/ AMC)

The finale featured special cameos

Many more people from behind the scenes ended up onscreen for the show’s swan song.

According to The Hollywood Reporter, when "Person to Person" screened during a series finale event attended by the show’s cast and crew, cameos from "Mad Men" producers and writers “(drew) drawing hoots, hollers and hysterics from the company and their pockets of comrades throughout the theater.”

One of the cameos included the show’s writer Semi Chellas, who was in the McCann Erickson meeting with Peggy and Stan (she's seated at his right).

Betty's final dress had significance to Matthew Weiner

Costume designer Janie Bryant revealed that Weiner had her choose a specific dress for the final time viewers would see Betty on the show.

“Matt had said to me, ‘I really would love for Betty to wear something that she’s worn before, not that she had gone out and bought new clothes as she was becoming very ill,” she said in a behind-the-scenes video for AMC.

“This really spoke to me because it is very rich but also very conservative, timeless, classic. She looks so beautiful,” Bryant said.

“I think it’s an amazing way to end Betty’s story. She’s going to live her life out being happy, smoking cigarettes.”

Betty Francis (January Jones) in her final scene in the series finale of "Mad Men."